Light source for plant cultivation

ABSTRACT

A plant cultivation light source includes at least two light sources selected from first, second, and third light sources that emit first, second, and third lights, respectively. The first light has a first peak at a wavelength from about 400 nanometers to about 500 nanometers, the second light has a second peak appearing at a wavelength, which is longer than the first peak, from about 400 nanometers to about 500 nanometers, and the third light has a third peak appearing at a wavelength, which is shorter than the first peak, from about 400 nanometers to about 500 nanometers. The first light is a white light and has a first sub-peak having an intensity lower than an intensity of the first peak at a wavelength from about 500 nanometers to about 700 nanometers. The first sub-peak has a full-width at half-maximum greater than a full-width at half-maximum of the first peak.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/713,918, filed on Apr. 5, 2022, which is a continuation of U.S.patent application Ser. No. 16/506,731, filed on Jul. 9, 2019, whichclaims priority to and benefits of U.S. Provisional Application No.62/850,122, filed on May 20, 2019. The disclosures of the aforementionedapplications are hereby incorporated by reference in their entireties.

BACKGROUND 1. Field of Disclosure

The present disclosure relates to a plant cultivation light source. Moreparticularly, the present disclosure relates to a light source thatemits a light optimized for plant photosynthesis.

2. Description of the Related Art

Various light sources, as an alternative to sunlight, are beingdeveloped and being used as lightings for plant cultivation.Conventionally, incandescent lamps and fluorescent lamps have beenmainly used as the lightings for plant cultivation. However, theconventional lightings for plant cultivation do not adequately provideplants with light having a wavelength band necessary for plantphotosynthesis.

In recent years, an LED is used as lighting devices for plantcultivation, however, there are problems in using the LED, such ashaving a spectrum limited to a specific wavelength or consumingexcessive energy and cost to provide a sufficient amount of light to theplants.

SUMMARY

Embodiments of the present disclosure provide a plant cultivation lightsource including at least two light sources selected from first, second,and third light sources respectively emitting first, second, and thirdlights. The first light has a first peak at a wavelength from about 400nanometers to about 500 nanometers. The second light has a second peakappearing at a wavelength, which is longer than the first peak, fromabout 400 nanometers to about 500 nanometers. The third light has athird peak appearing at a wavelength, which is shorter than the firstpeak, from about 400 nanometers to about 500 nanometers. The first lightis a white light and has a first sub-peak having an intensity lower thanan intensity of the first peak at a wavelength from about 500 nanometersto about 700 nanometers. The first sub-peak has a full-width athalf-maximum greater than a full-width at half-maximum of the firstpeak.

An overlap area between a spectrum of the light emitted from the lightsource and a spectrum defined by a McCree curve is equal to or greaterthan about 50% of the spectrum defined by the McCree curve.

The second light has a second sub-peak at a wavelength from about 500nanometers to about 600 nanometers, and an intensity of the secondsub-peak is higher than the first sub-peak.

The third light has a third sub-peak at a wavelength from about 500nanometers to about 600 nanometers, and an intensity of the thirdsub-peak is higher than the first sub-peak.

The light source further includes a fourth light source that emits afourth light having a fourth peak at a wavelength from about 600nanometers to about 700 nanometers.

At least one of the first to fourth light sources is provided in aplural number.

The first light has a color temperature of about 5000K.

According to embodiments, a plant cultivation light source moduleemploys the light source. The plant cultivation light source moduleincludes the light source emitting a light in a visible light wavelengthband according to the embodiments, a controller controlling the lightsource, and a power supply supplying a power to at least one of thelight source and the controller.

According to embodiments, the light source is employed in a plantcultivation device, and the plant cultivation device includes the lightsource module according to the embodiments and a housing in which thelight source module is installed.

According to the above, the light source according to theabove-mentioned embodiments may be used to provide the light to theplants and to cultivate the plants. The light source may provide thelight having the spectrum that is optimal for the photosynthesis of theplants. The spectrum of the mixed light obtained by mixing two or morelights of the first to fourth lights maximizes the area where thespectrum of the mixed light overlaps the McCree curve, and thus thelight efficiency may remarkably increase. Thus, it is possible toefficiently grow the plants with a small number of light sources, andenergy and cost may be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the present disclosure will becomereadily apparent by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is a plan view showing a plant cultivation light source accordingto an exemplary embodiment of the present disclosure;

FIG. 2 is a block diagram showing a plant cultivation light sourcemodule according to an exemplary embodiment of the present disclosure;

FIG. 3A is a graph showing spectra of lights respectively emitted from afirst light source and a second light source in the light sourceaccording to an exemplary embodiment of the present disclosure;

FIG. 3B is a graph showing a spectrum of a light obtained by mixing thelights respectively emitted from the first light source and the secondlight source and a spectrum of the McCree curve;

FIG. 4 is a block diagram showing a plant cultivation light sourcemodule according to an exemplary embodiment of the present disclosure;

FIG. 5A is a graph showing a spectrum of a light from a plantcultivation light source of FIG. 4 ;

FIG. 5B is a graph showing a spectrum of a light obtained by mixinglights respectively emitted from a first light source and a third lightsource and a spectrum of the McCree curve;

FIG. 6 is a block diagram showing a plant cultivation light sourcemodule according to an exemplary embodiment of the present disclosure;

FIG. 7A is a graph showing a spectrum of a light from a plantcultivation light source of FIG. 6 ;

FIG. 7B is a graph showing a spectrum of a light obtained by mixinglights respectively emitted from first, second, and third light sourcesand a spectrum of the McCree curve;

FIG. 8 is a block diagram showing a plant cultivation light sourcemodule according to an exemplary embodiment of the present disclosure;

FIG. 9A is a graph showing a spectrum of a light from a plantcultivation light source of FIG. 8 ;

FIG. 9B is a graph showing a spectrum of a light obtained by mixinglights respectively emitted from second and third light sources and aspectrum of the McCree curve; and

FIG. 10 is a perspective view conceptually showing a cultivation deviceaccording to an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

The present disclosure may be variously modified and realized in manydifferent forms, and thus specific embodiments will be exemplified inthe drawings and described in detail hereinbelow. However, the presentdisclosure should not be limited to the specific disclosed forms, and beconstrued to include all modifications, equivalents, or replacementsincluded in the spirit and scope of the present disclosure.

Like numerals refer to like elements throughout. In the drawings, thethickness, ratio, and dimension of components are exaggerated foreffective description of the technical content. It will be understoodthat, although the terms first, second, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms are only used to distinguish oneelement, component, region, layer or section from another region, layeror section. Thus, a first element, component, region, layer or sectiondiscussed below could be termed a second element, component, region,layer or section without departing from the teachings of the presentdisclosure. As used herein, the singular forms, “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise.

It will be further understood that the terms “comprises” and/or“comprising”, or “includes” and/or “including”, when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

The present disclosure relates to a light source used to cultivateplants.

Plants photosynthesize using a light in a visible light wavelength bandand gain energy through photosynthesis. Photosynthesis of plants doesnot occur to the same extent in all wavelength bands. The light in aspecific wavelength band that plants use for photosynthesis in sunlightis called Photosynthetic Active Radiation (PAR), occupies a portion ofsolar spectrum, and corresponds to a band from about 400 nanometers toabout 700 nanometers.

FIG. 1 is a plan view showing a plant cultivation light source accordingto an exemplary embodiment of the present disclosure, and FIG. 2 is ablock diagram showing a plant cultivation light source module accordingto an exemplary embodiment of the present disclosure.

Referring to FIGS. 1 and 2 , a plant cultivation light source module 100includes a light source 30 emitting a light that plants need, acontroller 40 controlling the light source 30, and a power supply 50supplying a power to the light source 30 and/or the controller 40. Thelight source 30 may include first and second light sources 31 and 33emitting a light in a visible light wavelength band and having aspectrum peak in different wavelengths from each other.

The first light source 31 and the second light source 33 may be disposedon a substrate 20. The substrate may be a printed circuit board on whichwirings and circuits are formed to allow the first light source 31 andthe second light source 33 to be directly mounted thereon, however, thesubstrate should not be limited to the printed circuit board. The shapeand the structure of the substrate should not be particularly limited aslong as the first light source 31 and the second light source 33 aremounted on the substrate, and the substrate may be omitted.

In the exemplary embodiment of the present disclosure, the controller 40is connected to the first and/or second light sources 31 and 33 tocontrol whether to operate or not the first light source 31 and thesecond light source 33. The controller 40 may be connected to the firstand/or second light sources 31 and 33 by wire or wirelessly. Thecontroller 40 is connected to the power supply 50 that supplies thepower to the controller 40. The power supply 50 may be connected to thelight source via the controller 40, or may be directly connected to thelight source to supply the power to the light source.

The controller 40 may control ON/OFF of the first light source 31 and/orthe second light source 33 such that the first light source 31 and thesecond light source 33 emit the lights at a predetermined intensity fora predetermine period. The first light source 31 and the second lightsource 33 may be individually operated such that the plants carry outphotosynthesis with a maximum efficiency. The controller 40 mayindependently control an emission intensity or an emission time of afirst light L1 and a second light L2. In addition, when the first lightsource 31 and/or the second light source 33 include a plurality of lightemitting diodes, the individual light emitting diodes may beindependently controlled.

In the exemplary embodiment of the present disclosure, when the firstand second light sources 31 and 33 include plural light emitting diodes,a composition ratio of the light emitting diodes may differ in variousways. For example, the number of the second light sources 33 may besmaller or larger than the number of the first light sources 31. Thenumber of the light emitting diodes of the first and second lightsources 31 and 33 may be determined according to the type of plants. Forinstance, the composition ratio may vary depending on a ratio ofcryptochrome that is a blue light receptor to phytochrome that is a redlight receptor. Accordingly, the light emitting diodes provided in thefirst and second light sources 31 and 33 may irradiate the lightscustomized to the type of plants. Therefore, plants may grow faster andbigger with less power.

In addition, the controller 40 may control the operation of the firstlight source 31 and the second light source 33 according to a presetprocess or according to a user's input. The operation of the first lightsource 31 and the second light source 33 may be changed in various waysdepending on the type of plants and the growth stage of plants.

According to the exemplary embodiment of the present disclosure, whenthe plant cultivation light source is used, it is possible toindependently provide a growing environment suitable for the types ofplants even under conditions in which the sunlight is insufficient orthe sunlight is not provided. In addition, plants with enhancedphotosynthetic capacity may be easily grown in large quantities.

FIG. 3A is a graph showing spectra of lights respectively emitted fromthe first light source 31 and the second light source 33 according to anexemplary embodiment of the present disclosure, and FIG. 3B is a graphshowing a spectrum of a light obtained by mixing the lights respectivelyemitted from the first light source 31 and the second light source 33and a spectrum of the McCree curve.

Referring to FIGS. 3A and 3B, the first light source 31 emits the firstlight L1 in a first wavelength band, and the second light source 33emits the second light L2 in a second wavelength band.

Both the first light source 31 and the second light source 33 emitlights in a wavelength band used for photosynthesis. The wavelength bandused for photosynthesis is within a range from about 400 nanometers toabout 700 nanometers. The light source according to an exemplaryembodiment of the present disclosure provides a light having a plantlighting efficiency equal to, or greater than about 3.1 μmols/J to theplants.

The first light L1 corresponds to a white light. In the presentexemplary embodiment of the present disclosure, the first light L1 maybe a light whose color temperature is about 5000K and may be a lighthaving the color temperature higher or lower than about 5000K. In thepresent exemplary embodiment of the present disclosure, the first lightL1 has a first peak P1 at a wavelength from about 400 nanometers toabout 500 nanometers and has a first sub-peak P1′ at a wavelength fromabout 500 nanometers to about 700 nanometers. The first peak P1 mayappear at a wavelength from about 400 nanometers to about 470nanometers, e.g., at a wavelength from about 430 nanometers to about 460nanometers. The first sub-peak P1′ may appear at a wavelength from about540 nanometers to about 600 nanometers.

The first peak P1 has the highest intensity in the spectrum of the firstlight L1, and the first sub-peak P1′ has an intensity lower than that ofthe first peak P1. A full-width at half-maximum of the first peak P1 isnarrower than a full-width at half-maximum of the first sub-peak P1′.

The second light L2 has a second peak P2 at a wavelength from about 400nanometers to about 500 nanometers and has a second sub-peak P2′ at awavelength from about 500 nanometers to about 700 nanometers. The secondpeak P2 may appear at a wavelength from about 450 nanometers to about500 nanometers, e.g., at a wavelength of about 480 nanometers. Thesecond sub-peak P2′ may appear at a wavelength from about 540 nanometersto about 610 nanometers.

The second peak P2 has the highest intensity in the spectrum of thesecond light L2, and the second sub-peak P2′ has an intensity lower thanthat of the second peak P2. A full-width at half-maximum of the secondpeak P2 is narrower than a full-width at half-maximum of the secondsub-peak P2′.

The second peak P2 appears at a wavelength longer than the first peakP1, and the second sub-peak P2′ appears at a wavelength band similar tothe first sub peak P1′. The intensity of the first peak P1 and theintensity of the second peak P2 may be similar to each other. The firstpeak P1 and the second peak P2 correspond to the blue light. In thepresent exemplary embodiment, since the first peak P1 and the secondpeak P2 do not appear at the same wavelength, the blue light of too highintensity may be prevented from being provided to the plants when thefirst light L1 and the second light L2 are combined with each other.

The second sub-peak P2′ may be emitted at an intensity higher than thatof the first sub-peak P1′. In this case, a height of the second sub-peakP2′ may be higher than a height of the first sub-peak P1′. The secondsub-peak P2′ lies from a green color to a yellow color and a portion ofa red color. Wavelength bands that are relatively effective forphotosynthesis correspond to blue and red colors: however, visible lightwavelength bands corresponding to other colors between the blue colorand the red color may also affect photosynthesis. For example, variouspigments in plants, such as carotenoids, may absorb lights in wavelengthbands that are not absorbed by chlorophyll, thereby dispersing thelights and preventing chlorophyll from being destroyed. In addition,since an absorption spectrum of chlorophyll does not completely coincidewith an action spectrum of a leaf, photosynthesis occurs to some extenteven in the green light not absorbed by chlorophyll. In the exemplaryembodiment of the present disclosure, as a spectrum corresponding to thegreen color to the red color is augmented by the second sub-peak P2′ ofthe second light L2, photosynthetic efficiency of plants for a varietyof lights may be improved.

The spectrum of the first light L1 has a valley between the first peakP1 and the first sub-peak P1′, and the spectrum of the second light L2has a valley between the second peak P2 and the second sub-peak P2′. Inthe spectrum of the first light L1 and the spectrum of the second lightL2, positions of two valleys do not match with each other, and thus thelight may be sufficiently provided to the plants in a regioncorresponding to the valley when the two lights are combined with eachother.

The light source of the present disclosure emits a light having aspectrum whose area overlaps a spectrum known as the McCree curve byabout 50% or more due to the combination of the first light L1 and thesecond light L2. The McCree curve spectrum shows a light in a wavelengthrange required for optimal growth of plants.

According to the McCree curve MC, the wavelength band of the lightrequired for photosynthesis of plants is evenly distributed in a rangeof about 400 nanometers to about 700 nanometers. Therefore, even whenusing artificial lighting such as LEDs, there is a need to provide alight having a uniform intensity distribution in the wavelength bandfrom about 400 nanometers to about 700 nanometers.

In the case of conventional lightings for plants, it was common for LEDsto provide a high intensity of light in a single wavelength band with anarrow full-width at half-maximum rather than emitting a light in anentire wavelength band. For example, the conventional lightings forplants often used a red light source and a blue light source, which emita red light at a wavelength of about 660 nanometers and a blue light ata wavelength of about 450 nanometers, respectively, and are believed tobe mainly used for photosynthesis. As another way, the conventionallightings for plants mainly used a light source obtained by mixing whitelight sources respectively having color temperatures of about 5000K and3000K, and a light source of a red wavelength band was further used.However, in the case of the conventional lightings for plants, it wasdifficult to provide photons to plants in the entire wavelength bandcorresponding to the McCree curve, and as a result, the photosyntheticefficiency was not high.

The lightings according to the exemplary embodiment of the presentdisclosure provide the light that best matches the McCree curve usinglightings having different spectra from each other, and particularly, alight source that emits a light of a spectrum having an area overlapratio of at least 50% or at least 70% is provided.

In an exemplary embodiment of the present disclosure, the light sourcemay be implemented in various ways. As an example, the light source maybe implemented by using light emitting diodes.

In an exemplary embodiment of the present disclosure, the spectrum ofthe light source for providing the light corresponding to the McCreecurve may be set differently from the above-described embodiment.

FIG. 4 is a block diagram showing a plant cultivation light sourcemodule 100 according to an exemplary embodiment of the presentdisclosure.

FIG. 5A is a graph showing a spectrum of a light from a plantcultivation light source of FIG. 4 , and FIG. 5B is a graph showing aspectrum of a light obtained by mixing lights respectively emitted froma first light source and a third light source and a spectrum of theMcCree curve.

Referring to FIGS. 4, 5A, and 5B, the plant cultivation light sourcemodule 100 includes a light source 30 including a first light source 31and a third light source 35, a controller 40, and a power supply 50.

In the present exemplary embodiment, both the first light source 31 andthe third light source 35 emit lights in a wavelength band used forphotosynthesis. The first light source 31 emits a first light L1, andthe third light source 35 emits a third light L3.

The first light L1 corresponds to a white light. In the presentexemplary embodiment of the present disclosure, the first light L1 maybe a light whose color temperature is about 5000K and may be a lighthaving the color temperature higher or lower than about 5000K. In thepresent exemplary embodiment of the present disclosure, the first lightL1 has a first peak P1 at a wavelength from about 400 nanometers toabout 500 nanometers and has a first sub-peak P1′ at a wavelength fromabout 500 nanometers to about 700 nanometers. The first peak P1 mayappear at a wavelength from about 400 nanometers to about 470nanometers, e.g., at a wavelength from about 430 nanometers to about 460nanometers. The first sub-peak P1′ may appear at a wavelength from about540 nanometers to about 600 nanometers.

The first peak P1 has the highest intensity in the spectrum of the firstlight L1, and the first sub-peak P1′ has an intensity lower than that ofthe first peak P1. A full-width at half-maximum of the first peak P1 isnarrower than a full-width at half-maximum of the first sub-peak P1′.

The third light L3 has a third peak P3 at a wavelength from about 400nanometers to about 500 nanometers and has a third sub-peak P3′ at awavelength from about 500 nanometers to about 700 nanometers. The thirdpeak P3 may appear at a wavelength from about 400 nanometers to about460 nanometers, e.g., at a wavelength of about 410 nanometers. The thirdsub-peak P3′ may appear at a wavelength from about 500 nanometers toabout 550 nanometers.

The third peak P3 has the highest intensity in the spectrum of the thirdlight L3, and the third sub-peak P3′ has an intensity lower than that ofthe third peak P3. A full-width at half-maximum of the third peak P3 isnarrower than a full-width at half-maximum of the third sub-peak P3′.

The third peak P3 appears at a wavelength shorter than that of the firstpeak P1, and the third sub-peak P3′ appears at a wavelength band similarto that of the first sub-peak P3′. The intensity of the first peak P1and the intensity of the third peak P3 may be similar to each other.

In the present exemplary embodiment, since the first peak P1 and thethird peak P3 do not appear at the same wavelength, the blue light oftoo high intensity may be prevented from being provided to the plantswhen the first light L1 and the third light L3 are combined with eachother.

The third sub-peak P3′ may be emitted at an intensity higher than thatof the first sub-peak P1′. In this case, a height of the third sub-peakP3′ may be higher than a height of the first sub-peak P1′.

The third sub-peak P3′ lies from a green color to a yellow color and hasa wavelength band closer to the green color. As a spectrum correspondingto the green color to the yellow color is augmented by the thirdsub-peak P3′ of the third light L3, the photosynthetic efficiency ofplants for a variety of lights may be improved.

The spectrum of the first light L1 has a valley between the first peakP1 and the first sub-peak P1′, and the spectrum of the third light L3has a valley between the third peak P3 and the third sub-peak P3′. Inthe spectrum of the first light L1 and the spectrum of the third lightL3, positions of two valleys do not match with each other, and thussufficient light may be provided to the plants in a region of thespectrum corresponding to the valley as the two lights are combined witheach other.

The lightings according to the exemplary embodiment of the presentdisclosure provide the light that best matches the McCree curve usinglights having different spectra from each other, and particularly, thelightings provide a light of a spectrum having an area overlap ratio ofat least 50% or at least 70%.

In an exemplary embodiment of the present disclosure, the spectrum ofthe light source for providing the light corresponding to the McCreecurve may be set differently from the above-described embodiment, and alight source with a different wavelength may be additionally combined.

FIG. 6 is a block diagram showing a plant cultivation light sourcemodule 100 according to an exemplary embodiment of the presentdisclosure.

FIG. 7A is a graph showing a spectrum of a light from a plantcultivation light source of FIG. 6 , and FIG. 7B is a graph showing aspectrum of a light obtained by mixing lights respectively emitted fromfirst, second, and third light sources and a spectrum of the McCreecurve.

Referring to FIGS. 6, 7A, and 7B, the plant cultivation light sourcemodule includes a first light source 31, a third light source 35, afourth light source 37, a controller 40, and a power supply 50.

The first light source 31 and the third light source 35 may besubstantially the same as the first and third light sources 31 and 35respectively shown in FIGS. 2 and 4 .

According to the present exemplary embodiment, the fourth light source37 emits a fourth light L4 having a fourth peak P4 appearing at awavelength from about 600 nanometers to about 700 nanometers. A peak ofthe fourth light L4 is located in a wavelength band corresponding to ared color. As a light corresponding to the red color is augmented to anentire spectrum by the fourth light L4 from the fourth light source 37,the photosynthetic efficiency of plants for a variety of lights mayimprove. The fourth light source 37 may have a peak in a range fromabout 640 nanometers to about 680 nanometers, for example, the fourthpeak P4 at a wavelength of about 660 nanometers.

The lightings from the light sources according to the exemplaryembodiment of the present disclosure provide the light that best matchesthe McCree curve using lights having different spectra from each other,and particularly, the lightings from the light sources provide a lightof a spectrum having an area overlap ratio of at least 50%, at least70%, or at least about 80%.

FIG. 8 is a block diagram showing a plant cultivation light sourcemodule 100 according to an exemplary embodiment of the presentdisclosure. FIG. 9A is a graph showing a spectrum of a light from aplant cultivation light source of FIG. 8 , and FIG. 9B is a graphshowing a spectrum of a light obtained by mixing lights respectivelyemitted from second and third light sources and a spectrum of the McCreecurve.

Referring to FIGS. 8, 9A, and 9B, the plant cultivation light sourcemodule includes a second light source 33, a third light source 35, acontroller 40, and a power supply 50.

The second light source 33 and the third light source 35 may besubstantially the same as the second and third light sources 33 and 35respectively shown in FIGS. 2 and 4 .

The lightings from the light sources according to the exemplaryembodiment of the present disclosure provide the light that best matchesthe McCree curve using lights having different spectra from each other,and particularly, the lightings provide a light of a spectrum having anarea overlap ratio of at least 50% or at least 70%.

As described above, the light sources according to the exemplaryembodiment of the present disclosure may be combined in various forms,and the form of the combination should not be limited to those describedabove. For example, the light sources according to the exemplaryembodiment of the present disclosure may include at least two lightsources among the first to third light sources or at least three lightsources among the first through fourth light sources. For example, thelight sources may include all the first through fourth light sources. Asanother example, the light sources may include the first, third, andfourth light sources. In the case where two or more light sources amongthe first through fourth light sources are combined with each other, theoverlap area between the spectrum of the light emitted from the lightsources and the spectrum defined by the McCree curve may be about 70% ormore as compared with the spectrum defined by the McCree curve. Asdescribed above, the spectrum of the mixed light obtained by mixing twoor more lights of the first through fourth lights maximizes the areawhere the spectrum of the mixed light overlaps the McCree curve, andthus the light efficiency may increase above about 3.1 μmol/J. Thus, itis possible to efficiently grow the plants with a small number of lightsources, and energy and cost may be reduced.

In the present exemplary embodiment, at least one light source among thefirst to fourth light sources may include a plurality of light emittingelements.

The light source according to the exemplary embodiment of the presentdisclosure may be used for plant cultivation, and in detail, the lightsource may be applied to a plant cultivation device or a green house inwhich a light source is installed.

FIG. 10 is a perspective view conceptually showing a cultivation deviceaccording to an exemplary embodiment of the present disclosure. Thecultivation device shown in FIG. 10 corresponds to a small-sizedcultivation device, but it should not be limited thereto or thereby.

Referring to FIG. 10 , the cultivation device 100′ according to theexemplary embodiment of the present disclosure includes a housing 60having an inner space capable of growing plants and a light source 30provided in the housing 60 to emit a light.

The housing 60 provides an empty space therein within which plants maybe provided and may be grown. The housing 60 may be provided in a boxshape that is capable of blocking an external light. In the exemplaryembodiment of the present disclosure, the housing 60 may include a lowercase 61 opened upward and an upper case 63 opened downward. The lowercase 61 and the upper case 63 may be coupled to each other to form thebox shape that blocks the external light.

The lower case 61 includes a bottom portion and a sidewall portionextending upward from the bottom portion. The upper case 63 includes acover portion and a sidewall portion extending downward from the coverportion. The sidewall portions of the lower case 61 and the upper case63 may have structures engaged with each other. The lower case 61 andthe upper case 63 may be coupled to each other or separated from eachother depending on a user's need, and thus a user may open or close thehousing 60.

The housing 60 may be provided in various shapes. For example, thehousing 60 may have a substantially rectangular parallelepiped shape ormay have a cylindrical shape. However, the shape of the housing 60should not be limited thereto or thereby, and the housing 60 may beprovided in other shapes.

The housing 60 provides an environment in which the plants providedtherein may be grown. The housing 60 may have a size that is capable ofaccommodating a plurality of plants provided and grown therein. Inaddition, the size of the housing 60 may be changed depending on a useof the plant cultivation device 100′. For example, in a case where theplant cultivation device 100′ is used for a small-scale plantcultivation for the purpose of in-home use, the size of the housing 60may be relatively small. In a case where the plant cultivation device100′ is used for commercial plant cultivation, the size of the housing60 may be relatively large.

In the present exemplary embodiment of the present disclosure, thehousing 60 may block the light such that the external light is notincident into the housing 60. Accordingly, a dark room environment,which is isolated from the outside, may be provided inside the housing60. Therefore, the external light may be prevented from beingunnecessarily irradiated to the plants provided inside the housing 60.In particular, the housing 60 may prevent an external visible light frombeing irradiated to the plants. Alternatively, or additionally, thehousing 60 may be designed to be partially open depending on needs inorder to receive the external light.

In the present exemplary embodiment, the space inside the housing 60 maybe provided as a whole space. However, this is for the convenience ofexplanation only, and the space inside the housing 60 may be dividedinto a plurality of compartments. That is, partition walls may beprovided in the housing 60 to divide the space inside the housing 60into plural compartments.

The light source provides the light to the plants in the space of thehousing 60. The light source is disposed on an inner surface of theupper case 63 or the lower case 61. In the exemplary embodiment of thepresent disclosure, the light source may be disposed on the coverportion of the upper case 63. In the present exemplary embodiment, thelight source disposed on an inner surface of the cover portion of theupper case 63 is shown: however, it should not be limited thereto orthereby. For example, according to another embodiment of the presentdisclosure, the light source may be disposed on the sidewall portion ofthe upper case 63. In addition, according to another embodiment of thepresent disclosure, the light source may be disposed on the sidewallportion of the lower case 61, e.g., on an upper end of the sidewallportion. Further, according to another embodiment of the presentdisclosure, the light source may be disposed on at least one of thecover portion of the upper case 63, the sidewall portion of the uppercase 63, and the sidewall portion of the lower case 61.

A culture platform 70 may be provided in the space of the housing 60 tocultivate the plant easily, for example, for facilitating a hydroponicculture. The culture platform 70 may include a plate-shaped plate 71disposed at a position spaced apart upward from the bottom portion ofthe housing 60. A through-hoes 73 with a uniform size may be providedthrough the plate 71. The culture platform 70 may be provided to allowplants to be grown on an upper surface of the plate 71 and may include aplurality of through-holes 73 to allow water supplied thereto to bedrained when the water is supplied. The through-hole 73 may be providedin a size such that plants do not slip through. For example, thethrough-hole 73 may have a diameter smaller than plants. A space betweenthe culture platform 70 and the bottom portion of the lower case 61 mayserve as a water tank in which the drained water is stored. Accordingly,water drained downward through the through-hole 73 of the cultureplatform 70 may be stored in the space between the bottom portion of thelower case 61 and the culture platform 70.

However, according to the exemplary embodiment of the presentdisclosure, plants may also be cultivated by methods other than thehydroponic culture method. In this case, water, a culture medium, andsoil may be provided in the space of the housing 60 to supply the waterand/or nutrients necessary for the plants, and the housing 60 may serveas a container. The culture medium or the soil may contain the nutrientsfor plants to grow, such as potassium (K), calcium (Ca), magnesium (Mg),sodium (Na), and iron (Fe). Plants may be provided while being imbeddedin the culture medium or may be placed on a surface of the culturemedium depending on its type.

The culture platform 70 may have a size and a shape, which varydepending on the shape of the housing 60 and the manner that a firstlight source and a second light source are provided. The size and theshape of the culture platform 70 may be configured to allow plantsprovided on the culture platform 70 to be placed within an irradiationrange of the light irradiated from the first light source and the secondlight source.

The housing 60 may include a water supply unit disposed therein tosupply water to the plants. The water supply unit may be configured tobe disposed at an upper end of the housing 60, e.g., on the innersurface of the cover portion of the upper case 63, and to spray wateronto the culture platform 70. However, the configuration of the watersupply unit should not be limited thereto or thereby, and theconfiguration of the water supply unit may vary depending on the shapeof the housing 60 and the arrangement of the culture platform 70. Inaddition, the user may directly supply water into the housing 60 withouta separate water supply unit.

One or more of the water supply units may be provided. The number of thewater supply units may vary depending on the size of the housing 60. Forinstance, in the case of the relatively small-sized plant cultivationdevice for in-home use, a single water supply unit may be used since thesize of the housing is small. In the case of the relatively large-sizedcommercial plant cultivation device, plural water supply units may beused since the size of the housing 60 is large. However, the number ofthe water supply units should not be limited thereto or thereby, and thewater supply unit may be provided in a variety of positions in variousnumbers.

The water supply unit may be connected to a water tank provided in thehousing 60 or a faucet outside the housing 60. In addition, the watersupply unit may further include a filtration unit such that contaminantsfloating in water are not provided to the plants. The filtration unitmay include a filter, such as an activated carbon filter or a non-wovenfabric filter, and thus water passing through the filtration unit may bepurified. The filtration unit may further include a light irradiationfilter. The light irradiation filter may remove germs, bacteria, fungalspores, and the like, which are present in water, by irradiating anultraviolet light or the like to the water. As the water supply unitincludes the above-mentioned filtration unit, there is no possibilitythat the inside of the housing 60 and plants are contaminated even whenthe water is recycled or rainwater or the like is directly used for thecultivation.

Water provided from the water supply unit may be provided as plain wateritself (for example, purified water) without additional nutrients:however, it should not be limited thereto or thereby, and the waterprovided from the water supply unit may contain nutrients necessary forthe growth of the plant. For example, water may contain a material, suchas potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), and iron(Fe), and a material, such as nitrate, phosphate, sulfate, and chloride(Cl). For instance, Sachs's solution, Knop's solution, Hoagland'ssolution, or Hewitt's solution may be supplied from the water supplyunit.

According to the exemplary embodiment, plants may be cultivated using alight source.

A plant cultivation method according to an exemplary embodiment of thepresent disclosure may include germinating a plant and providing lightin the visible light wavelength band to the germinated plant. The lightprovided to the plants is emitted from the light sources according tothe above-described embodiments, and the light in the visible lightwavelength band may include at least two or three lights among first,second, third, and fourth lights having different light spectra fromeach other.

Although the exemplary embodiments of the present disclosure have beendescribed, it is understood that the present disclosure should not belimited to these exemplary embodiments but various changes andmodifications can be made by one ordinary skilled in the art within thespirit and scope of the present disclosure as hereinafter claimed.

Therefore, the disclosed subject matter should not be limited to anysingle embodiment described herein, and the scope of the presentinventive concept shall be determined according to the attached claims.

We claim:
 1. A light emitting device, comprising: a substrate; a firstlight emitter disposed on the substrate and configured to emit a firstlight having a first peak at a wavelength from about 400 nm to about 500nm and a first sub-peak having a full-width at half-maximum greater thata full-width at half-maximum of the first peak; and a second lightemitter disposed on the substrate and configured to emit a second lighthaving a second peak at a wavelength from about 500 nm to about 700 nm,the second peak having an intensity greater than an intensity of thefirst sub-peak of the first light; a controller electrically connectedto the first light emitter and the second light emitter; and a powersupply electrically connected to the first light emitter and the secondlight emitter and configured to supply power to the first light emitterand the second light emitter, wherein the first sub-peak and the secondpeak are located at different wavelengths from each other in spectrum ofthe first light and the second light, wherein a spectrum of a combinedlight obtained by mixing the first light and the second light has afirst valley between the first peak and the first sub-peak, and whereinan intensity of the first peak in the spectrum is lower than anintensity of the second peak in the spectrum.
 2. The light emittingdevice of claim 1, wherein the intensity of the first peak in thespectrum is higher than an intensity of the first sub-peak in thespectrum.
 3. The light emitting device of claim 1, wherein a combinationof the first light and the second light has a lower intensity in thefirst peak as compared to a case when the first light is combined with athird light having a third peak at the wavelength from about 400 nm toabout 500 nm.
 4. The light emitting device of claim 1, wherein thesubstrate comprises a circuit to allow the first light emitter and thesecond light emitter to be directly mounted on the substrate.
 5. Thelight emitting device of claim 1, wherein the spectrum of the combinedlight obtained by mixing the first light and the second light has asecond valley between the first peak and the second peak.
 6. The lightemitting device of claim 5, wherein the first valley and the secondvalley do not overlap with each other and light is provided in regionscorresponding to the first valley and the second valley.
 7. The lightemitting device of claim 1, wherein the second light has a secondsub-peak at a wavelength less than 700 nm and an intensity of the secondsub-peak is lower than the intensity of the second peak.
 8. A lightemitting device, comprising: a substrate; a first light emitter disposedon the substrate and configured to emit a first light having a firstpeak at a wavelength from about 400 nm to about 500 nm and a firstsub-peak having a full-width at half-maximum greater that a full-widthat half-maximum of the first peak; and a second light emitter disposedon the substrate and configured to emit a second light having a secondpeak at a wavelength different from that of the first sub-peakwavelength, the second peak having an intensity greater than anintensity of the first sub-peak of the first light; a controllerelectrically connected to the first light emitter and the second lightemitter; and a power supply electrically connected to the first lightemitter and the second light emitter and configured to supply power tothe first light emitter and the second light emitter, wherein the firstsub-peak and the second peak are located at different wavelengths fromeach other in spectrums of the first light and the second light, whereina spectrum of a combined light obtained by mixing the first light andthe second light has a first valley between the first sub-peak and thesecond peak, and wherein an intensity of the first peak in the spectrumis lower than an intensity of the second peak in the spectrum.
 9. Thelight emitting device of claim 8, wherein the intensity of the firstpeak in the spectrum is higher than an intensity of the first sub-peakin the spectrum.
 10. The light emitting device of claim 8, wherein acombination of the first light of and the second light has a lowerintensity in the first peak as compared to a case when the first lightis combined with a third light having a third peak at the wavelengthfrom about 400 nm to about 500 nm.
 11. The light emitting device ofclaim 8, wherein the substrate comprises a circuit to allow the firstlight emitter and the second light emitter to be directly mountedthereon.
 12. The light emitting device of claim 8, wherein the secondlight has a second sub-peak at a wavelength less than 700 nm and anintensity of the second sub-peak is lower than the intensity of thesecond peak.
 13. The light emitting device of claim 8, wherein anoverlap area between a spectrum of the first light and the second lightand a spectrum defined by a McCree curve is equal to or greater than thespectrum defined by the McCree curve by about 50%.
 14. The lightemitting device of claim 8, wherein the first light has a cool colortemperature
 15. A cultivation device, comprising: a housing having alower portion and an upper portion disposed over the lower portion; asubstrate disposed in the housing; a first light emitter disposed on thesubstrate and configured to emit a first light having a first peak at awavelength from about 400 nm to about 500 nm and a first sub-peak havinga full-width at half-maximum greater that a full-width at half-maximumof the first peak; and a second light emitter disposed on the substrateand configured to emit a second light having a second peak at awavelength different from that of the first sub-peak wavelength, thesecond peak having an intensity greater than an intensity of the firstsub-peak of the first light; a controller electrically connected to thefirst light emitter and the second light emitter; and a power supplyelectrically connected to the first light emitter and the second lightemitter and configured to supply power to the first light emitter andthe second light emitter, wherein the first sub-peak and the second peakare located at different wavelengths from each other in spectrums of thefirst light and the second light, wherein a spectrum of a combined lightobtained by mixing the first light and the second light has a firstvalley between the first peak and the first sub-peak, and wherein anintensity of the first peak in the spectrum is lower than an intensityof the second peak in the spectrum.
 16. The cultivation device of claim15, wherein the housing comprises a cultivation structure disposed at aposition spaced apart upward from the lower portion of the housing. 17.The cultivation device of claim 16, wherein the cultivation structureincludes a through-hole to allow a plant to be grown on an upper surfaceof the cultivation structure.
 18. The cultivation device of claim 15,wherein the intensity of the first peak in the spectrum is higher thanan intensity of the first sub-peak in the spectrum.
 19. The cultivationdevice of claim 15, wherein a combination of the first light of and thesecond light has a lower intensity in the first peak as compared to acase when the first light is combined with a third light having a thirdpeak at the wavelength from about 400 nm to about 500 nm.
 20. Thecultivation device of claim 15, wherein the second light has a secondsub-peak at a wavelength less than 700 nm and an intensity of the secondsub-peak is lower than the intensity of the second peak.